1. Field of the Invention
The present invention relates to a receiving apparatus, a program and a receiving method.
2. Description of the Related Art
In recent years, wireless communication systems on the basis of the IEEE (Institute of Electrical and Electronic Engineers) 802.11 Standard have become widespread. Wireless communication apparatuses, including transmitting apparatuses and receiving apparatuses which form these wireless communication systems, are advantageous in comparison with wired communication systems in that they have freedom, such as portability.
In addition, as described in the International Publication No. 2006-020520, a 20 MHz mode using a frequency band having a bandwidth of 20 MHz, a 40 MHz mode using a frequency band having a bandwidth of 40 MHz, an upper 40 MHz mode using a frequency band of 20 MHz on the upper side of the 40 MHz mode, or a lower 40 MHz mode using a frequency band of 20 MHz on the lower side of the 40 MHz mode are assumed as band modes used for wireless communication in IEEE 802.11n. Accordingly, it is necessary for the receiving apparatuses to determine which band mode the received wireless signal corresponds to so as to carry out a decoding process in accordance with the determined band mode when a wireless signal is received.
As the method for determining the band mode of a wireless signal, a method for providing a receiving apparatus with two types of band-pass filters for sampling a signal component in the frequency band corresponding to the upper 40 MHz mode and the lower 40 MHz mode (for example, band-pass filters having pass-bands of −20 MHz to 0 MHz and 0 MHz to 20 MHz) and inputting a wireless signal that has been converted to a baseband signal into each band-pass filter can be cited. In the case where only a signal component in the frequency band corresponding to the upper 40 MHz mode is sampled from the baseband signal, it can be determined to be the upper 40 MHz mode, and in the case where only a signal component in the frequency band corresponding to the lower 40 MHz mode is sampled from the baseband signal, it can be determined to be the lower 40 MHz mode.